There is a surgery that involves thinly stripping a part of a living tissue. Such surgery includes a case where tissue is required to be removed from a living body or where partially stripped tissue is not removed and allowed to remain clinging to the living body after surgery. In both the cases, it is preferable that the stripped surface of tissue is as smooth as possible. In particular, it is preferable that a stripped piece is uniform in thickness.
When a tissue part to be stripped is muscle or skin, a surgical knife or similar, which is comparatively easy to manipulate can be used. However, in the case of sites such as a blood vessel or eyeball sclera, the area of tissue to be stripped is small and, therefore, a knife with a very small blade is used.
It is preferable that a knife for stripping a part of tissue cut sharply. However, in view of the specialty of stripping tissue so thinly, a problem is raised; that is, a too sharp knife may cut tissue in the depth direction, so it may be required to correct manipulation at each time, which may result in a roughness of the stripped surface, thereby making it difficult to obtain a smooth surface.
For example, in surgery for glaucoma, Schlemm's canal is incised and aqueous humor is discharged, thereby reducing ocular tension. Schlemm's canal is located near and under the scleral spur. Accordingly, the surgery is performed as follows: the sclera is incised into a substantially rectangular shape except for the side located next to the cornea. Then the sclera is stripped from the incised portion toward the remaining side, thereby forming a valve or flap from the stripped sclera, thus leaving the sclera in the living body.
When stripping sclera as described above, a knife generally called “a golf knife” is used. A golf knife includes: a substantially linear shank attached to a handle; and a plate-shaped blade disposed at the leading end of the shank and has an axis that inclines with respect to the axis of the flat surface of the shank. This knife therefore has a shape similar to a golf club, in a plan view.
The cutting edge of the golf knife is formed at a periphery of the plate-shaped blade. Using this cutting edge, the sclera is incised and the incised site is stripped. This cutting edge has a sharp leading end formed by grinding the periphery of the blade in the direction of the thickness of the blade. Therefore, the cutting edge has a cross-section of triangular in which a sharp leading end is located substantially in the middle in the direction of the thickness from the surfaces of a plate forming the blade.
Sclera has a relatively high strength. Sclera may be stripped by moving the knife sideways in alternate directions. This may result in roughening of the surface of the sclera stripped by the golf knife. Therefore, the golf knife used for stripping sclera is generally buffed or suchlike in order to blunt its edge forcibly.
In cataract surgery, the cornea is incised and a lens is inserted. Generally, the knife used to incise the cornea requires great sharpness (see Patent Document 1, for example).
Heart surgery for removing fat from around a blood vessel also uses a golf knife as described above (in heart surgery, it is generally called a “hockey knife”). In this type of surgery, using the cutting edge of the golf knife, fat adhering to a blood vessel is stripped and collected toward one side.
Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 2005-334054